1. Field of the Invention
The invention relates to a drive chain, more particularly to a drive chain having a durable construction and enhanced protection against dust.
2. Description of the Related Art
Referring to FIG. 1, a conventional drive chain 1 is shown to include a plurality of parallel pairs of outer chain plates 16, a plurality of parallel pairs of inner chain plates 13, a plurality of parallel pairs of tubular rollers 12, a plurality of pins 14 and a plurality of bushings 15. Each of the outerchain plates 16 is formed with a pair of first pin holes 161. Each of the inner chain plates 13 is formed with a pair of second pin holes 131. Each of the pairs of the inner chain plates 13 is disposed between two adjacent pairs of the outer chain plates 16 such that one of the second pin holes 131 in each of the inner chain plates 13 is aligned with the first pin holes 161 in one of the adjacent pairs of the outer chain plates 16, and such that the other one of the second pin holes 131 is aligned with the first pin holes 161 in the other one of the adjacent pairs of the outer chain plates 16. Each of the pairs of rollers 12 is disposed between a corresponding one of the pairs of the inner chain plates 13 such that the rollers 12 in each of the pairs are aligned respectively in an axial direction with the second pin holes 131 in the corresponding one of the pairs of the inner chain plates 13. Each of the pins 14 extends axially through a respective one of the rollers 12 and through aligned ones of the first and second pin holes 161,131. Each of the bushings 15 is sleeved on a respective one of the pins 14 and has a respective one of the rollers 12 sleeved thereon. Each of the bushings 15 has opposite ends that abut against one of the pairs of the inner chain plates 13, respectively.
Some of the drawbacks of the aforesaid conventional drive chain 1 are as follows:
1. Most of the components of the drive chain 1 are made of metal to result in a strong construction. As such, lubricant is needed to ensure smooth pivoting movement among the components of the drive chain 1. However, since the pivot joints among the inner and outer chain plates 13, 16 and the pins 14 of the drive chain 1 are exposed, dust can easily get trapped and collect on the lubricant present in clearances that are formed by the pivot joints. In addition, the lubricant can be undesirably released via the aforesaid clearances when the drive chain 1 is in use. As such, the operation of the drive chain 1 is adversely affected, and the service life of the same is accordingly reduced.
2. When the drive chain 1 is in use, two opposite pulling forces are applied by the inner and outer chain plates 13, 16 on the pins 14. The resulting shearing force can cause damage to the pins 14.
Therefore, the object of the present invention is to provide a drive chain that is capable of overcoming the aforesaid drawbacks commonly associated with the prior art.
According to the present invention, a drive chain comprises:
a plurality of parallel pairs of outer chain plates, each of the outer chain plates being formed with a pair of first pin holes;
a plurality of parallel pairs of inner chain plates, each of the inner chain plates being formed with a pair of second pin holes, each of the pairs of the inner chain plates being disposed between two adjacent pairs of the outer chain plates such that one of the second pin holes in each of the inner chain plates is aligned with the first pin holes in one of the adjacent pairs of the outer chain plates, and such that the other one of the second pin holes in each of the inner chain plates is aligned with the first pin holes in the other one of the adjacent pairs of the outer chain plates;
a plurality of parallel pairs of tubular rollers, each of the pairs of the rollers being disposed between a corresponding one of the pairs of the inner chain plates such that the rollers in each of the pairs are aligned respectively in an axial direction with the second pin holes in the corresponding one of the pairs of the inner chain plates; and
a plurality of pins, each of which extends axially through a respective one of the rollers and through aligned ones of the first and second pin holes.
In one embodiment, each of the inner chain plates is formed with a pair of annular rims that are disposed respectively around the second pin holes and that extend in the axial direction away from the rollers so as to abut against two adjacent ones of the outer chain plates. Each of the outer chain plates is formed with a peripheral flange that extends in the axial direction toward the rollers so as to abut against two adjacent ones of the inner chain plates and that retains pivotally one of the annular rims on each of the two adjacent ones of the inner chain plates.
In another embodiment, each of the inner chain plates is formed with a pair of outer annular rims that are disposed respectively around the second pin holes and that extend in the axial direction away from the rollers so as to abut against two adjacent ones of the outer chain plates. Each of the outer chain plates is formed with a pair of inner annular rims that are disposed respectively around the first pin holes and that extend in the axial direction toward the rollers and into a respective one of the outer annular rims.
In a further embodiment, each of the outer chain plates is formed with a pair of first annular rims that are disposed respectively around the first pin holes and that extend in the axial direction toward the rollers and into a respective one of the second pin holes. Each of the inner chain plates is formed with a pair of second annular rims that are disposed respectively around the second pin holes and that extend in the axial direction toward the rollers so as to abut against the corresponding one of the pairs of the rollers.